Switch



A 24, 1934 E. o. scnwsirzsn SWITCH 'OOlnuonurn u amnion Origin Filed OC't. 3, 1929 Patented Apr. 24, 1934 UNITED STATES SWITCH Edmund 0. Schweitzer, Northbrook, Ill.

Original application October 3, 1929, Serial No. 396,976, now Patent No. 1,921,005, dated August Divided and this application December 4, 1930, Serial No. 499,872

3 Claims. (Cl. 200-145) application is a division of my Patent'No. 1,921,005, dated 'Aug. 8, 1933.

The present invention relates in general to switches or circuit interrupters and more partic- 'ularly to such switches as are adapted to interrupt large currents and are preferably immersed in a bath of insulating oil or other are quenching liquid.

Electric switches should be designed so that upon opening a heavy short circuit the resulting arc is extinguished in the shortest possible time. There are a'large number of known factors detezmined by the switch design that control the rate at which the' arc is extinguished. Among these factors may be mentioned the speed of separation of the contacts, the number of breaks in series, and the means provided for cooling or I quenching the arc.

It is an'object of the present invention to provide a switch wherein the contact breaking parts will interrupt the circuit by drawing a plurality of arcs in series in a simple and expedient manner.

It is a further object of the present invention to provide a rugged and economical switch of the class above indicated which may be used in a fused cut-out.

The attainment of the above and further objects of the present invention will be apparent from the following specification taken in conjunction with 3 the accompanying drawing forming a part thereof. In the drawing, the single figure is a view of a protective system utilizing a fused cut-out which includes a switch of my improved construction.

In this figure, a fused cut-out is indicated dia- 5 grammatically at 1.

ing 2 within which the various switching parts are mounted, said casing being adapted to be filled with a suitable insulating and are quenching liquid and provided with a cover indicated at 3. A fuse link 4 is mounted m a chamber 5 of suitable insulating material, the chamber being suitably mounted within the casing-'2' and beingprovided with a tight fitting cover 6. The chamber 5 is illed with an insulating arc extinguishing liquid such as oil, carbon tetra-chloride, ether, or the" like. This liquid is preferably one having a high temperature coefiicient o expansion. A bellows '7 is mounted within the casing 2, said bellows being of any approved construction. A commu- 5 nicating connection 8 connects the chamber 5 with the;bellows 7, so that upon expans'ionof the fiuid in the chamber 5 the fluid causes the expansion of the bellows 7. The bellows is fixed at its upper end and is provided with an operating member or 55 rod 9 for actuating a switch 10.

The cut-out comprises a cascircuit is :open.

A line conductor 20 which extends to asource of power enters the cut-out 1 and is connected to the fuse link 4. From the fuse link the circuit extends through a conductor 21 to the switch 10, thence crosswise through the springs of the swich to a terminal 55 and a conductor 15 which extends to the primary side of an oil filled transformer 25 that is connected, by a conductor 26, to a source of power.

In the cut-out herein shown I have provided means for disconnecting the primary side of the transformer when the temperature of the transformer rises above a predetermined value, and. this regardless of whether the rise in temperature is due to an overload on the secondary side or due to some defect within the transformer. A bulb is emersed in the transformer casing, said bulb being connected by means of a thin tube 31 to the receptacle 5 within which the fuse 4 is mounted. The bellows 7, the casing 5, the tube 31 and the bulb 30 are all filled with the same insulating liquid. Expansion of this liquid, brought about by heating of the fuse due to a small but continuing overload on the system, or an overheating of the transformer 25 due to an internal defect, wi expand the bellows 7 so that the lower operating member 9 of the bellows actuates the arm 16 of the switch 10 to actuate the switch to open the circuit.

A description will now be given of the construction of 1 .8 switch 10. This switch comprises a number of leaf springs of current conducting material, said springs being mounted as cantilevers. The leaf springs are indicated at 50 and are mounted at one end and spaced apart by insulation indicated at 51. The springs are shown in the switch-closed position by the full lines and in the switch-open position by the dotter lines. A conductor such as the conductor 15 is connected to a terminal block 55 which is connected to the uppermost spring 50. A conductor such as 21 is connected to the other terminal of the switch circuit, said terminal being indicated at 56. When the springs areunstressed the The switch is arranged to be held closed by a member 9 of insulating material.

When the insulating member 9 is raised a slight amount the springs 50 separate slightly thus introducing one or more small arcs in the circuit. Upon further upward mov ment of the operating member 9' further separation of the springs take place thereby increasing the num- "ber of arcs and increasing the size of the arcs...

The first mm be formed is formed between the above it. Uponiurther separation of the springs this are is increased in length until the second lowermost spring 50 assumes its normal position as shown in the dotted lines. Further upward movement of the insulating. member 9' causes the third spring from the bottom to separate from the second bottom-most spring thus drawing another arc; When this spring reaches its normal position as is shown by the dotted lines the next spring separates, this drawing still another arc, and so forth until the current flow through the circuit is interrupted and the arcs go out. It is of course tobe understood that if desired the contact 56 may be located somewhat below the location shown in Figure 2 whereby the first arc is drawn between the lowermost spring and the contact. The oil or other insulating liquid surrounding the arcs tends to cool them quickly and in addition the leaf springs 50, from which the arcs extend, being good conductors of heat, help to conduct the heat of the are away from the point of current interruption thus serving to accelerate the cooling action and tending to deionize the are quickly and cause its extinguishment. It is to be noted that the contact springs 50 are arranged so that their free ends diverge from one another when the springs are in their normal open circuit position. Any are that may be drawn between two adjacent springs intermediate the ends thereof is blown outwardly by the magnetic action resulting from the current flow. As the arc is blown outwardly its length is increased. It is also being blown into fresh cool oil. All of this facilitates the rapid cooling and resultant extinguishment of the arc.

While switches of the present invention are particularly useful in conection with cut-outs of the kind herein shown, they are not limited to such use, it being within the purview of the present invention to use switches of the kind herein shown in cut-outs of specifically diflerent constructions, or in circuit interrupters not employing iuses or expansible bellows.

In compliance with the requirements of the patent statutes I have herein shown and described a preferred embodiment of my invention. It is, however, to be understood that the invention is not limited to this precise construction but is capable of modification, the embodiment herein shown being merely illustrative of the general principles or my invention. What I consider new and desire to secure by Letters Patent is:

1. An electric switch comprising at least three leaf springs mounted at one end adjacent but separate from one another, the opposite ends of the springs being free of one another, means for flexing the free ends of the springs towards one another into engagement whereby a circuit is established between the end springs and crosswise through the intermediate springs, said springs separating under their own resiliency upon the release of said means to draw a plurality of series connected arcs between the end springs and the intermediate springs, said springs extending divergent of one another outwardly of their mounted ends whereby the total length of the gaps between the outer ends of the springs is substantially greater than the total of the distances between the springs at their mounted ends.

2. An electric switch including a terminal member having a stationary contact, a plurality of leaf springs rigidly mounted at one end with the free end of the first spring adjacent the contact and the free ends of the successive springs successively further from the contact, a stack of insulators between the mounted ends of the springs, the springs diverging from one another outwardly of the insulator stack, whereby the length of the gaps between the free ends of the springs is substantially greater than the length of the insulator stack, and means for flexing the free ends of the springs into engagement with one another and the first spring into engagement with the contact to establish a circuit crosswise through the springs to the contact, the circuit being interrupted upon retraction 01' said means by the separation of the springs under their own resiliency, all of the springs first moving away from the contact to draw one arc and, as the respective springs successively reach their normal position drawing additional arcs between the springs.

33. In combination, a plurality of leaf springs mounted at one end in spaced insulated relation and diverging from their mounted ends, wedge shaped insulators separating the springs at their mounted ends, terminal means connected to one of the outer springszonly at one end of the group of springs, terminal means connected to one of the outer springs only on the opposite side oi the group of springs and the opposite end of said group, the intervening springs being free of circuit connection throughout when said springs are separated, and means for pressing the divergent free ends of said springs together to close a circuit between said terminals, said last means being releasable whereby said springs draw a plurality of series arcs between said terminals.

' EDMUND O. SCHWEITZER. 

